DE 31 30 185 A1 discloses a disc brake with resetting springs. The disc brake includes two resetting springs spaced in a circumferential direction and abutting with free spring legs on brake pads arranged on either side of the brake disc. The brake pads are lifted from the brake disc after a brake operation due to the spreading effect of the spring legs. The springs are compressed between a brake holder, a brake caliper and the brake pads in a first assembly. The resetting springs are anchored only insufficiently in the disc brake so that the resetting springs may easily be detached and lost, especially when exposed to vibrations. In a second design, the resetting springs are screwed to the disc brake. However, this necessitates an undesirable additional fastening means for each resetting spring. In addition, the use of two resetting springs basically involves the risk that in the event of failure of one of the resetting springs there will occur an inclined position of a brake pad which impairs functioning.
In view of the above, an object of the present invention is to disclose a spot-type disc brake with a spring assembly for the clearance adjustment at one brake pad, which overcomes the shortcomings known from the state of the art and, in addition, is easy to handle.
This object of the present invention is achieved by a spot-type disc brake assembly which includes a brake housing straddling a brake disc, with at least one brake pad that is arranged in the brake housing so as to be slidable in the actuating direction and cooperates tribologically with the brake disc upon brake application. At least one actuating device to apply an actuating force to the brake pad is incorporated in the brake housing. To adjust a clearance between the brake pad and the brake disc upon termination of brake application, the spot-type disc brake includes a spring assembly which comprises exactly one spring that is secured detachably to the spot-type disc brake and is supported on the brake pad, on the one hand, and on the brake housing, on the other hand. In particular the detachable attachment of the spring on a brake housing permits an especially simple manipulation of the subassembly composed of brake housing, brake pad, and spring. Also, the spring is easy to mount and dismount.
An advantageous embodiment of the spot-type disc brake is achieved in that the spring extends substantially in the central plane of the brake housing with respect to the circumferential direction of the brake disc. Thus, an undesirable inclined positioning of the brake pad is avoided even in the extremely unlikely case of failure of the spring. In any case, the general braking function will not be impaired, not even when such a failure occurs.
A preferred variation of the spot-type disc brake is achieved when the spring is supported on a brake pad which directly cooperates with at least one actuating device. This relates to spot-type disc brakes both in a fixed-type caliper and a floating-caliper construction, with a floating-caliper disc brake including a corresponding actuating device only on one side of the brake disc. The action of the spring directed to the brake pad close to the actuating device has a particularly positive effect on the clearance adjustment.
To facilitate the ability of mounting and dismounting of the spring, it may be provided that the spring with a first end portion is inserted into an accommodation recess at the brake pad. The end portion of the spring is fixed within the accommodation recess so as to prevent the end portion from slipping out of the accommodation recess. Above all in arrangements of the spot-type disc brake wherein two or more actuating devices apply a brake force to the brake pad, it is appropriate that the first end portion of the spring is supported in a circumferential direction between two actuating devices on the brake pad. This achieves a symmetrical application of the spring force to the brake pad and prevents an inclined positioning of brake pads.
In an expedient embodiment, the spring is configured as a tension spring that is suspended with a second end portion on the brake housing. A tension spring of this type is a standard component permitting low-cost application in the spring assembly of the present invention. The tension spring is preferably made of helical wire and suspended with a second end portion in a brake housing bore, for example. According to an alternative variation, the spring may of course also be designed as a compression spring which is detachably fastened on the brake housing.
Another favorable spring variation is achieved because the spring is configured as a spiral leg spring which is detachably fastened with a second end portion on the brake housing and acts as a bending spring. Above all, such a leg spring necessitates little mounting space and can be adapted flexibly to any respective installation specifications by simple shaping measures at its free ends. More particularly, the spring legs are configured in conformity with the preset supporting points on the brake housing or on the brake pad. It is suitable above all in this connection that at least one spring portion is shaped at the spring and supported on the brake housing in a circumferential direction. This improves anchoring of the spring on the brake housing, and lateral tilting of the spring with respect to the circumferential direction is prevented.